Heats Without a Heater! The HydroMate II heater/pump heats the water using the wasted heat from the pump motor. This eliminates expensive heaters and reduces operating costs. Operates on 120 Volts! All softubs can be plugged into a standard 120 Volt 15 Amp outlet. Ozone Water Sanitizing! All models come with a water sanitizing unit built directly into the HydroMate II pump! This system utilizes ozone to oxidize contaminants in the water during heating and filtration cycles.